Although many cognitive functions are affected in Alzheimer's disease (AD), episodic memory and semantic retrieval have particular clinical relevance. Tests of episodic memory (delayed recall and recognition) are highly sensitive for detecting AD, and tests of semantic retrieval (naming and fluency) are best for staging the disease and tracking its progression. In the proposed research, we will document the anatomical and physiological correlates of these impairments in living subjects in order to gain insights into the distribution of the underlying anatomical and functional brain lesions that produce AD. To pusue this approach, and extend understanding of brain-behavior relations in aging and AD, we plan to conduct a series of experiments relating cognitive test performance in two domains (episodic memory and semantic retrieval) to two imaging measures: hippocampal volume, assessed with high-resolution magnetic resonance imaging, and patterns of neural activation, assessed with functional MRI.